It's hard to keep personal issues quiet when you're a presidential candidate. It's even harder if you're Hillary Clinton. Her early departure from a 9/11 memorial service forced her hand about her pneumonia.

She's not the only high-profile politician who wanted to keep her illness private. But for perspective, here are some past presidents who kept serious ailments from the public eye.

Grover Cleveland

According to a Men's Health article, Cleveland informed the public he'd be attending a fishing trip, but actually underwent surgery to remove a tumor, five teeth and part of his jaw.

Woodrow Wilson

The 28th president suffered a stroke while in office in October 1919. Men's Health explains that afterwards, he was forced to withdraw from public view. His wife, Edith, assumed many of his duties.

Undoubtedly one of the most cleverly laid smoke screens ever put down around a politician.

John R. Bumgarner, about JFK

John F. Kennedy

Despite his apparent youth and energy, JFK suffered from Addison's Disease.He often suffered from back pain so severe that he struggled to "climb a flight of stairs or even put on his own socks."

Franklin Delano Roosevelt

FDR contracted Polio during his time in office. He hid his condition by walking with "a cane and leaning on an aide to guide him to and from his car or a podium for a speech," according to Men's Health.

Hillary's health scare doesn't even get close to how these presidents hid their illness